The present invention generally relates to video signal recording and/or reproducing apparatuses having a function of carrying out assembled recordings, and more particularly to a video signal recording and/or reproducing apparatus which carries out an assembled recording by once stopping the recording operation, moving a tape in a reverse direction over a predetermined distance and then resuming the tape travel in a forward direction so as to start a new recording in continuance with a previous recording. The video signal recording and/or reproducing apparatus according to the present invention is designed to minimize an overlap between the previous recording and the new recording.
Generally, in a video signal recording and/or reproducing apparatus and especially in a video signal recording and/or reproducing apparatus which records an image-picked up video signal from a television camera on a tape, the apparatus is frequently operated in such a manner that the recording operation is temporarily stopped during the recording operation and the recording operation is resumed thereafter. It is common to operate the apparatus in this manner when using a portable television camera and recording the image-picked up video signal on the tape by a portable recording and/or reproducing apparatus.
When the power source switch is turned OFF in order to temporarily stop the recording operation while recording the image-picked up video signal from the television camera related to a certain picture, rotary heads stop rotating and the tape stops traveling. Thus, the tape which is drawn out of a cassette and is loaded into a predetermined tape path within the apparatus when the recording is started, is drawn back into the cassette and is unloaded. Hence, when the mode of the apparatus is set to the recording mode and the tape is drawn out of the cassette and is loaded into the predetermined tape path so as to resume the recording of the image-picked up video signal related to another picture, the tape position with respect to the heads before the tape unloading operation will not accurately coincide with the tape position after the tape is loaded again to resume the recording operation. Accordingly, when the recording operation is resumed after carrying out the tape unloading and loading operations as described above, an unrecorded part may be formed on the tape between a previously recorded part and a newly recorded part, or an overlapping part may be formed on the tape when the recording is resumed from a part overlapping the previously recorded part.
In order to eliminate the unwanted deviation in the tape position introduced during the tape unloading and loading operations, the tape is maintained in the state loaded in the predetermined tape path during predetermined modes of the apparatus, that is, measures are taken to prevent the tape from being unloaded during the predetermined modes of the apparatus. However, even when such measures are taken to maintain the tape in the loaded state, the traveling tape does not stop immediately after an operation is carried out to temporarily stop the tape, due to inertia of a tape feeding system. As a result, the tape actually stops after traveling over a certain distance. Further, when resuming the tape travel so as to resume the recording operation, it will take a certain time period for the tape traveling speed to reach a predetermined tape traveling speed. Accordingly, when the recording operation is resumed by simply resuming the tape travel from a position where the tape stopped, stable recording cannot be carried out during the initial period of the resumed recording operation. Thus, when a tape recorded in this manner is played, the servo operation becomes unstable at a joint part between the two recordings, that is, at the part where the recording is temporarily stopped and then resumed thereafter. Therefore, there is a problem in that the reproduced picture will become distorted at the joint part. In addition, when the recording operation is resumed after the tape travel is resumed and the tape traveling speed has reached the predetermined tape traveling speed, an unrecorded part will be formed on the tape between the previously recorded part and the newly recorded part, and the reproduced picture will become unsatisfactory for viewing between the two recording parts.
In order to prevent such problems from being introduced when the recording operation is temporarily stopped, a supply reel is automatically rotated in a tape take-up direction so as to rewind a predetermined quantity of tape before stopping the tape. By taking such a measure, the tape traveling speed will reach the predetermined tape traveling speed while the tape travel is resumed and the tape travels over a distance approximately corresponding to the rewound quantity of tape, when the recording operation is resumed. Moreover, the new recording can be carried out satisfactorily in continuance with the previously recorded part when the recording operation is resumed after the tape traveling speed has reached the predetermined tape traveling speed.
The assembled recording in which the recording operation is once stopped, the tape is moved in the reverse direction over a predetermined distance and stopped, and the tape is then moved in the forward direction and the new recording is started after the tape has traveled in the forward direction over the predetermined distance, is disclosed in U.S. patent applications Ser. No. 404,395 and Ser. No. 496,129, now U.S. Pat. Nos. 4,573,090 and 4,554,604 respectively, in which the assignee is the same as the assignee of the present application, for example.
When rewinding the tape over the predetermined distance and stopping the tape after the recording operation is once stopped, and when moving the tape over the predetermined distance and starting the new recording after the tape travel is resumed, the number of control pulses reproduced from the tape is counted in order to detect that the tape has traveled over the predetermined distance. Alternatively, the number of pulses generated from a frequency generator which is coupled to a capstan motor, is counted to detect that the tape has traveled over the predetermined distance.
However, the tape traveling speed is extremely low when the tape is being stopped and when the tape is being started to travel. For this reason, the reproduction of the control pulses, the generation of the pulses by the frequency generator, and the counting of the pulses cannot be performed accurately during these times. As a result, it is impossible to accurately detect whether the tape has traveled over the predetermined distance during these times. Accordingly, in order to prevent an unrecorded part from being formed between the end of the previously recorded part and the start of the newly recorded part, the conventional apparatus starts the new recording before the end of the previous recording is reached. In other words, when the tape is rewound over the predetermined distance and the tape travel is then resumed in the forward direction, the new recording is started from a position overlapping a part of the previous recording. For example, in the actual conventional apparatus, this overlap between the previous recording and the new recording on the tape exists over a distance corresponding to three to four the video signal frames.
At the overlap between the previous recording and the new recording, the pre-recorded signals of the previous recording are substantially erased by the new signals of the new recording, but an interference is introduced in the color signal. Hence, a reproduced picture having a satisfactory picture quality cannot be obtained from the overlap. In order to obtain a reproduced picture having a satisfactory picture quality, it is desirable that the overlap is extremely small or does not exist. However, in the conventional apparatus, the overlap is made intentionally as described before so as to reduce the chances of an unrecorded part being formed between the previous recording and the new recording.